Wood Fibers for Enhanced Binding in Growing Media

ABSTRACT

A plant growth media composition, articles made therefrom, and methods of making and using the same are described. The plant growth media composition includes a combination of one or more plant growth substrate materials and an additive such as cellulose fibers, clay, carrageenan, alginate, chitosan, or combinations thereof.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No.62/450,799, filed under 35 U.S.C. § 111(b) on Jan. 26, 2017, thedisclosure of which is incorporated herein by reference in its entiretyfor all purposes.

BACKGROUND OF THE INVENTION

Commercial polymer cross-linked substrate plugs, such as Preforma, Omniplugs, GrowTech, and IHT, have been made in factories based onpolyurethane glue chemistry. However, these growing media need to betransported to nurseries, and the production processes often involvechemical emissions of polyurethane binders, such as toluene diisocyanate(TDI) and methylene diphenyl diisocyanate (MDI). Polyurethane bindersare also not completely biodegradable. The transportation of premadegrowing media filled in trays adds extra costs for growers, andsometimes the short shelf life of such plugs may also cause logisticissues. Therefore, there is a need in the art for improved stabilizedgrowing media for transplanting, so that growing media can be made uponneed in situ, in nurseries, without the need for advanced productiontechnology, and by using environmentally friendly and compostableadditives/binders.

SUMMARY OF THE INVENTION

Provided is a stabilized growing media that holds together and may beused in transplanting robots or in nursery/greenhouses. Also providesare methods of making and using the stabilized growing media.

Provided is a plant growth media composition that includes a one or moreplant growth substrate materials and a binder or additive such ascellulose fibers, clay, carrageenan, chitosan, alginate, or combinationsthereof.

In a first aspect, provided is a plant growth media compositioncomprising cellulose fibers and one or more plant growth substratematerials. In certain embodiments, the composition comprises cellulosefibers, clay, and one or more plant growth substrate materials. Incertain embodiments, the composition comprises cellulose fibers,carrageenan, and one or more plant growth substrate materials. Incertain embodiments, the composition comprises cellulose fibers, one orboth of alginate and chitosan, and one or more plant growth substratematerials.

In certain embodiments, the plant growth substrate materials compriseone or more of peat, coir, pine or other barks, perlite, compost,fertilizers, minerals such as vermiculite, manure, granulated lava,pumice, burnt or calcined clay, mineral fibers, Sphagnum moss,Hypnaceous moss, rice hulls, bagasse, sand, leaf mold, gypsum, andlimestone. In certain embodiments, the substrate materials comprise finewhite peat, perlite medium grade, and vermiculite fine grade. In certainembodiments, the substrate materials comprise coir, Spaghnum peat, andperlite. In certain embodiments, the substrate materials comprise finepeat and medium perlite.

In certain embodiments, the cellulose fibers are present in an amountranging from about 0.1% w/w to about 40% w/w. In certain embodiments,the cellulose fibers are present in an amount ranging from about 1% w/wto about 20% w/w. In certain embodiments, the cellulose fibers arepresent in an amount ranging from about 5% w/w to about 10% w/w.

In certain embodiments, the cellulose fibers comprise a mixture ofcellulose and lignocellulose. In certain embodiments, the cellulosefibers consist essentially of cellulose. In certain embodiments, thecellulose fibers consist essentially of lignocellulose.

In certain embodiments, the cellulose fibers have an average length thatranges from about 10 μm to about 5 mm, and an average width that rangesfrom about 1 μm to about 500 μm. In certain embodiments, the cellulosefibers have a density ranging from about 0.5 g/cm³ to about 5 g/cm³. Incertain embodiments, the cellulose fibers have an equilibrium moisturecontent ranging from about 5% to about 15%. In certain embodiments, thecellulose fibers have a length-to-width ratio greater than about 10.

In certain embodiments, the plant growth media composition has amoisture content, before addition of water, of from about 35% to about45%. In certain embodiments, the plant growth media composition furtherincludes a sufficient amount of water to render the moisture content ofthe plant growth composition in a range of from about 65% to about 70%.

In certain embodiments, the plant growth media composition has a pHranging from about 5.5 to about 6.8. In certain embodiments, the plantgrowth media composition has a pH of about 5.8. In certain embodiments,the plant growth media composition is in the form of expanded pellets,flat filled trays, mini blocks, or press pots.

In certain embodiments, the plant growth media composition furthercomprises a wetting agent. In certain embodiments, the plant growthmedia composition further comprises an additional binder selected fromthe group consisting of polyvinyl alcohol (PVA) and polyvinyl acetate(PVAC). In particular embodiments, the plant growth media compositionfurther comprises a crosslinker. In particular embodiments, thecrosslinker comprises an aldehyde, a thermo setting resin, or a salt ofa multi-variant anion. In particular embodiments, the crosslinkercomprises tripolyphosphate, citrate, glyoxal, isocyanate, orpoly(acrylic acid) bis(hydroxyethyl) sulfone (BHES). In certainembodiments, the plant growth media composition further comprises aplasticizer selected from the group consisting of glycerol, phthalateesters, ethylene glycol, diethylene glycol, polyethylene glycols,propylene glycols, polypropylene glycols, 1,3-butylene glycol,1,3-propanediol, urea, trimethylamine hydrochloride, pentanediol, blockcopolymers of polyoxypropylene, hexitols, and oxyalkylene derivatives ofhexitols.

In certain embodiments where the composition comprises cellulose fibersand clay, the cellulose fibers and clay are present at a weight ratio ofcellulose fibers to clay ranging from about 1:1 to about 5:1. In certainembodiments where the composition comprises cellulose fibers and clay,the clay is present in an amount ranging from about 10 kg/m³ ofsubstrate materials to about 65 kg/m³ of substrate materials. In certainembodiments where the composition comprises cellulose fibers and clay,the clay is present in an amount ranging from about 35 kg/m³ ofsubstrate materials to about 40 kg/m³ of substrate materials.

In another aspect, provided is a plant growth media compositioncomprising carrageenan and one or more plant growth substrate materials.In certain embodiments, the plant growth substrate materials comprisepeat, coir, pine or other barks, perlite, compost, fertilizers,vermiculite, manure, granulated lava, pumice, burnt or calcined clay,mineral fibers, Sphagnum moss, Hypnaceous moss, rice hulls, bagasse,sand, leaf mold, gypsum, limestone, or a combination thereof. In certainembodiments, the carrageenan comprises kappa-carrageenan,lambda-carrageenan, iota-carrageenan, or a combination thereof. Incertain embodiments, the carrageenan is present in an amount rangingfrom about 0.1% w/w to about 10% w/w, or from about 0.3% w/w to about 5%w/w, or from about 0.5% w/w to about 2% w/w. In certain embodiments, thecomposition further comprises alginate and/or chitosan. In certainembodiments, the composition further comprises a crosslinker compriseschitosan, calcium, tripolyphosphate, glutaraldehyde, adipic dihydrazide,water soluble carbodiimide, a metal, or combinations thereof. In certainembodiments, the composition includes carrageenan, cellulose fibers, andchitosan.

In another aspect, provided is a plant growth media compositioncomprising alginate, chitosan, or a combination thereof, and one or moreplant growth substrate materials. In certain embodiments, the plantgrowth substrate materials comprise one or more of peat, coir, pine orother barks, perlite, compost, fertilizers, vermiculite, manure,granulated lava, pumice, burnt or calcined clay, mineral fibers,Sphagnum moss, Hypnaceous moss, rice hulls, bagasse, sand, leaf mold,gypsum, limestone, or a combination thereof. In certain embodiments, thechitosan is present in an amount ranging from about 0.1% w/w to about10% w/w, or from about 0.3% w/w to about 5% w/w, or from about 0.5% w/wto about 2% w/w. In certain embodiments, the alginate is present in anamount ranging from about 0.1% w/w to about 10% w/w, or from about 0.3%w/w to about 5% w/w, or from about 0.5% w/w to about 2% w/w.

In another aspect, provided is a method of making a stabilized growingmedia, the method comprising mixing cellulose fibers with one or moreplant growth substrate materials to form a fibrous mixture, configuringthe fibrous mixture into a desired shape, and adding water to thefibrous mixture to activate binding in the fibrous mixture and form astabilized growing media of the desired shape. In certain embodiments,the method further comprises allowing the stabilized growing media todry for a period of time. In particular embodiments, the period of timeranges from about 30 minutes to about 24 hours. In particularembodiments, the period of time ranges from about 24 hours to about 36hours. In certain embodiments, the one or more plant growth substratematerials comprise peat, coir, pine or other barks, perlite, compost,fertilizers, minerals such as vermiculite, manure, granulated lava,pumice, burnt or calcined clay, mineral fibers, Sphagnum moss,Hypnaceous moss, rice hulls, bagasse, sand, leaf mold, gypsum, andlimestone. In certain embodiments, the configuring comprises fillingplug molds in a tray with the fibrous mixture. In certain embodiments,the stabilized growing media is able to withstand mechanicaltransplanting processes.

In another aspect, provided is a method of making a stabilized growingmedia, the method comprising mixing carrageenan, chitosan, alginate, ora combination thereof with one or more plant growth substrate materialsto form a fibrous mixture, configuring the fibrous mixture into adesired shape, and adding water to the fibrous mixture to activatebinding of the fibrous mixture and produce a stabilized growing media ofthe desired shape. In certain embodiments, the method further comprisesallowing the stabilized growing media to dry for a period of time. Inparticular embodiments, the period of time ranges from about 30 minutesto about 24 hours. In particular embodiments, the period of time rangesfrom about 24 hours to about 36 hours. In certain embodiments, the oneor more plant growth substrate materials comprise peat, coir, pine orother barks, perlite, compost, fertilizers, minerals such asvermiculite, manure, granulated lava, pumice, burnt or calcined clay,mineral fibers, Sphagnum moss, Hypnaceous moss, rice hulls, bagasse,sand, leaf mold, gypsum, and limestone. In certain embodiments, theconfiguring comprises filling plug molds in a tray with the fibrousmixture. In certain embodiments, the stabilized growing media is able towithstand mechanical transplanting processes.

In another aspect, provided is a kit for making a stabilized growingmedia. The kit includes a first container housing a substrate mix, and asecond container housing cellulose fibers, clay, carrageenan, alginate,chitosan, or a combination thereof. In certain embodiments, the kitfurther includes an additional binder or additive.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file may contain one or more drawings executedin color and/or one or more photographs. Copies of this patent or patentapplication publication with color drawing(s) and/or photograph(s) willbe provided by the U.S. Patent and Trademark Office upon request andpayment of the necessary fees.

FIGS. 1A-1C: Photographs showing a test of plugs made with the cellulosefibers Arbocel® FT 400 (5% w/w) in Jiffy Blend #10. After 3 days withrepeated watering, the plugs were still holding together nicely.

FIGS. 2A-2C: Photographs showing test of plugs made with the cellulosefibers Arbocel® FT 400 at 5% w/w (FIG. 2A), 10% w/w (FIG. 2B), and 20%w/w (FIG. 2C) on Jiffy Blend #3 and Jiffy Blend #10 high coirpercentage. FIG. 2A and FIG. 2C show plugs made with Jiffy Blend #3,while FIG. 2B shows plugs made with Jiffy Blend #10.

FIG. 3: Photograph of vegetative geranium cuttings showing extensionroot development in the substrate 8 days after “sticking” un-rootingcuttings.

FIGS. 4A-4B: Photographs showing weighing of Jiffy Blend #30 (FIG. 4A)and H1000 cellulose fibers (FIG. 4B) in the preparation of a fibrousmixture.

FIGS. 5A-5B: Photographs showing the mixing of Jiffy Blend #30 withH1000 cellulose fibers, during (FIG. 5A) and after (FIG. 5B) mixing toobtain a homogenous fibrous mixture.

FIG. 6: Photograph of tray filled with substrates made from fibrousmixtures of Jiffy Blend #30 and H1000, during initial watering.

FIGS. 7A-7C: Photographs showing IMADA modulus testing device used formeasuring breaking point of substrate plugs (FIG. 7A) and examplesubstrate plugs after breaking point measurements were taken (FIG. 7B),and chart showing breaking point measurement results (FIG. 7C).

FIG. 8: Photograph showing a comparison between a plug comprising 2% w/wH1000 (left) and a plug comprising 2% w/w H1000 and Pelbon clay (35-40kg/m³) (right) 2.5 weeks after planting.

FIGS. 9A-9B: Photographs of plugs which include 2% w/w ETF, which iscellulose fiber that is insoluble in water. FIG. 9A shows the traysfilled with plants, and FIG. 9B shows the plugs removed from the trays,with the roots of the plants visible.

FIG. 10: Photograph comparing plant growth in plugs which, from left toright, include ETF (2% w/w), the cellulose fibers 105B (2% w/w), anundisclosed binder (2% w/w), and a mixture of alginate (1% w/w) andchitosan (1% w/w).

FIG. 11: Photograph comparing plant root development and substratebinding between a plug that includes 2% w/w H1000 cellose fibers (left)and a Preforma plug with no cellulose fibers (right).

DETAILED DESCRIPTION OF THE INVENTION

Throughout this disclosure, various publications, patents, and publishedpatent specifications are referenced by an identifying citation. Thedisclosures of these publications, patents, and published patentspecifications are hereby incorporated by reference into the presentdisclosure in their entirety to more fully describe the state of the artto which this invention pertains.

In accordance with the present disclosure, a plant growth material isprepared by combining one or more plant growth substrate materials withone or more binders or additives such as cellulose fibers, clay,carrageenan, alginate, and chitosan. The plant growth material may befurther hydrated to produce a stabilized growing media. Using additivessuch as cellulose fibers, clay, carrageenan, alginate, and/or chitosan,different types of substrate plugs, press pots, pellets, and the likecan be stabilized and made in nursery. The plugs have demonstratedimprovements in physical and chemical characteristics, as well as inplant growth and toxicity tests, and have enabled surprisingly fastrooting of plants. Advantageously, the resulting material can beproduced in situ in nurseries, as an alternative to factory-producedsubstrate-based plugs for plant growth.

In some embodiments, the plant growth material composition includescellulose fibers and clay. It has been found that the combination ofcellulose fibers and and clay works to provide cation exchange andimprove water management while providing excellent strength and nutrientdelivery to plants in growing media. Cellulose fibers add moisture,tensile strength, and porosity, which allows plant roots to intertwinebetter, while clay provides stabilization and cation exchange for moreefficient nutrient delivery to the plant, with the overall combinationproviding improved water management by dispelling water more evenly. Asdemonstrated in the examples herein, and shown in FIG. 8, plant growthis enhanced in substrates comprising a combination of cellulose fibersand clay compared to substrates comprising cellulose fibers withoutclay, and substrates comprising a combination of cellulose fibers andclay stick together better over time than substrates comprisingcellulose fibers without clay. Moreover, as demonstrated in the examplesherein, substrates comprising cellulose fibes and clay strengthen inbinding over time and repeated watering and drying cycles which simulatea greenhouse environment.

The substrate materials usable to make the plant growth mediacompositions include, but are not limited to: peat, coir, pine or otherbarks, perlite, compost, fertilizers, minerals such as vermiculite,manure, granulated lava, pumice, burnt or calcined clay, mineral fibers,Sphagnum moss, Hypnaceous moss, rice hulls, bagasse, sand, perlite, leafmold, gypsum, limestone, and other growing media. A combination of twoor more plant growth substrate materials is generally known as asubstrate mix. Non-limiting examples of suitable commercially availablesubstrate mixes include Jiffy Seedling Mix 17-1 (composed of white peat,perlite, and vermiculite), Jiffy 7 QSM (quick soil mix without netting),Jiffy Blend #3 (comprising coir and peat), Jiffy Blend #10 (70% coir,26% spaghnum peat, 4% perlite), Jiffy Seedling Mix 17-3 (70% peat, 20%perlite, 10% vermiculite), and Jiffy Blend #30 (70% Canadian sphagnumpeat, 20% coir, and 10% perlite).

The term “cellulose fibers” as used herein encompasses cellulose fibers,lignocellulose fibers, and mixtures of cellulose fibers andlignocellulose fibers, unless otherwise noted. Cellulose is apolysaccharide found in the cell wall of plants. Lignocellulose is acomplex of cellulose, hemicellulose, and the aromatic polymer lignin. Insome embodiments, the cellulose fibers consist of cellulose fibers. Insome embodiments, the cellulose fibers consist of lignocellulose fibers.In some embodiments, the cellulose fibers comprise a mixture ofcellulose fibers and lignocellulose fibers.

Cellulose and lignocellulose are obtainable from a wide variety ofsustainable, plant-based raw materials. Natural cellulose fibers arealready used in a wide variety of applications, including: for paper andboard production; as an additive for tissue production; in the plasticsindustry for thermoplastics, WPC, duroplastics (melamine and phenolicresin molding compounds), and elastomers (rubber and rubber seals); inglues; in break pads; in floor coverings (e.g., laminates, rubberflooring); in enzyme production, such as in washing powder and animalfeed; and in pore creators and stabilizers for technical ceramics. Thecellulose fibers usable herein can include cellulose products in theform of functional cellulose fibers, cellulose additives, powderedcellulose, fine cellulose, micronized cellulose, cellulose compactates,cellulose flour, cellulose granulates, cellulose mixtures, cellulosecompounds, cellulose derivatives, cellulosic ethanol (CE),methylcellulose (MC), hydroxypropyl methylcellulose (HPMC), cellulosegels, cellulose wadding, cellulose insulation materials, or mixturesthereof.

The term “fiber” conventionally refers to a particulate material whereinthe length-to-width (or diameter) ratio of such particulate material isgreater than about 10. However, it is understood that the cellulosefibers herein need not strictly adhere to this definition. The averagelength-to-width ratio of the cellulose fibers herein is typicallygreater than about 10, but, in some embodiments, the averagelength-to-width ratio of the cellulose fibers is less than 10. Thecellulose fibers can have an average length that ranges from about 10 μmto about 5 mm, and an average width that ranges from about 1 μm to about500 μm. In some embodiments, the cellulose fibers include softwoodcellulose fibers that have an average width of about 35 μm. In someembodiments, the cellulose fibers include hardwood cellulose fibers thathave an average width of about 18 μm. In some embodiments, the cellulosefibers have an average length ranging from about 1 cm to about 8 cm. Insome embodiments, the cellulose fibers have an average length of about 2mm

The cellulose fibers can have a density ranging from about 0.5 g/cm³ toabout 5 g/cm³. In one non-limiting example, the cellulose fibers have adensity of about 1.5 g/cm³. The equilibrium moisture content of thecellulose fibers can range from about 5% to about 15%, or from about 8%to about 12%. In one non-limiting example, the equilibrium moisturecontent of the cellulose fibers is about 10%.

In some embodiments, the cellulose fibers are organic fibers producedfrom the chemical disintegration of fir and beech woods. However,numerous other methods of producing suitable cellulose fibers areencompassed by the present disclosure. In some embodiments, thecellulose fibers are physiologically and toxilogically harmless.

Non-limiting examples of suitable cellulose fibers include thosecommercially available under the Arbocel® brand name, such as Arbocel®400, FI 400, FIF 400, FT 400, and H1000, as well as those under theLignocel® brand name such as Lignocel CO 3-6. Arbocel® is anall-cellulose material. Arbocel® fibers have increased caliper/bulk, andimproved formation and profile, enlarged stiffness, and increasedporosity compared to other cellulose fiber products. Arbocel® is anon-toxic, biodegradable organic binder system with no dangerousemissions or other environmental concerns. All of the ingredients in theArbocel® material are used safely in the food or pharmaceuticalindustries. The Arbocel® material can be added as a solid additive tothe substrate materials. However, though Arbocel® and Lignocel®materials are identified for exemplary purposes, other cellulose fiberproducts can be used, including cellulose fiber products that are morewater soluble than Arbocel® or Lignocel® and therefore can be added tothe substrate materials in the form of a suspension or emulsion.

As noted, the combination of cellulose fibers and clay producessurprisingly advantageous results. A wide variety of clays may be usedas an extra binder, but also to provide cation exchange capacity, makingthe resulting media more efficient in delivering nutrients to plants. Insome embodiments, the clay is a bentonite clay, which is an absorbentaluminum phyllosillicate clay containing silicates and elemental oxides.Bentonite clay principally comprises the clay material montmorillonite.However, other clays can also be used. Non-limiting examples of othersuitable clays include hectorite clays, leonardite clays, and smectiteclays. One non-limiting of a suitable clay that is commerciallyavailable is clay sold under the brand name Pelbon from AMCOL BioAg.Pelbon clay is a calcium bentonite that contains minor amounts ofquartz, feldspar, and mica. Pelbon clay typically contains 60.5% SiO₂,18.2% Al₂O₃, 5.25% Fe₂O₃, 3.26% MgO, 3.14% CaO, 0.20% Na₂O, 0.14% K₂O,and 4.85% LOI.

In general, the cellulose fibers are added to the substrate materials tobe present in the fibrous mixture in an amount ranging from about 0.1%to about 40% (w/w), or from about 1% to about 20% (w/w), or from about5% to about 10% (w/w), based on the total weight of the fibrous mixture(before any water is added). When clay is present, the clay is added tothe substrate materials and cellulose fibers to be present in thefibrous mixture in an amount ranging from about 10 kg/m³ of substrate toabout 65 kg/m³ of substrate, or from about 25 kg/m³ of substrate toabout 50 kg/m³ of substrate, or from about 35 kg/m³ of substrate toabout 40 kg/m³ of substrate.

The cellulose fibers and clay may be present in the fibrous mixture in aweight ratio of cellulose fibers to clay of from about 0.25:1 to about10:1, or from about 0.75:1 to about 7:1, or from about 1:1 to about 5:1.The optimal ratio of cellulose fibers to clay may depend on theparticular combination of substrate materials in the composition.

The plant growth media composition may include one or more carrageenans.Carrageenan is a family of linear sulfated polysaccharides extractedfrom red edible seaweeds. Carrageenans are widely used in the foodindustry for their gelling, thickening, and stabilizing properties,including in dairy and meat products, due to their strong binding offood proteins. There are three main varieties of carrageenan, whichdiffer in their degree of sulfation. Kappa-carrageenan has one sulfategroup per disaccharide, iota-carrageenan has two sulfate groups perdisaccharide, and lambda-carrageenan has three sulfate groups perdisaccharide. The carrageenan may be added to the composition in anamount ranging from about 0.1% w/w to about 10% w/w, or from about 0.3%w/w to about 5% w/w, or from about 0.5% w/w to about 2% w/w.

In some embodiments, the plant growth media composition comprises acombination of cellulose fibers and carrageenan. As demonstrated in theexamples herein, it has been found that plugs made with a combination ofcellulose fibers and carrageenan strengthen over repeated watering anddrying cycles that simulate a greenhouse environment. In onenon-limiting example, the plant growth media composition comprisessubstrate materials, cellulose fiber in an amount of from about 0.5% w/wto about 2% w/w, and carrageenan in an amount of from about 0.5% w/w toabout 2% w/w.

The plant growth media composition may include one or more biopolymerssuch as, but not limited to, chitosan or alginate. As shown in theexamples herein, chitosan and alginate help to strengthen thecomposition. Chitosan and/or alginate may be present in an amounts,individually or combined, ranging from about 0.1% w/w to about 10% w/w,or from about 0.3% w/w to about 5% w/w, or from about 0.5% w/w to about2% w/w.

In one non-limiting example, the plant growth media compositioncomprises substrate materials, cellulose fibers in an amount rangingfrom about 0.5% w/w to about 2% w/w, carrageenan in an amount rangingfrom about 0.5% w/w to about 2% w/w, and chitosan in an amount rangingfrom about 0.% w/w to about 2% w/w. In another non-limiting example, theplant growth media composition comprises substrate materials,carrageenan in an amount ranging from about 0.5% w/w to about 2% w/w,and chitosan in an amount ranging from about 0.% w/w to about 2% w/w.

In another non-limiting example, the plant growth media compositioncomprises substrate materials, cellulose fibers in an amount of about 2%w/w, and carrageenan in an amount of about 2% w/w. As shown in theexamples herein, it is has been found that the combination of cellulosefibers and carrageenan can produce a plant growth media compositionwhich dramatically increases in strength over time in a greenhouseenvironment (i.e., following repeated cycles of watering and drying).

In another non-limiting example, the plant growth media compositioncomprises substrate materials, cellulose fibers in an amount of about 1%w/w, carrageenan in an amount of about 1% w/w, and chitosan in an amountof about 1% w/w. This combination has been found to produce a plantgrowth media composition which significantly increases in strength overtime, and contains less additive by weight than the combination of 2%cellulose fibers and 2% carrageenan. In other embodiments, the plantgrowth media composition comprises substrate materials, cellulose fibersin an amount of about 1% w/w, carrageenan in an amount of about 0.5%w/w, and chitosan in an amount of about 0.5% w/w. This combinationresults in a significant increase in strength over time, though not assignificant as the combination of substrate materials, 1% w/w cellulosefibers, 1% w/w carrageenan, and 1% w/w chitosan.

In another non-limiting example, the plant growth media compositioncomprises substrate materials, 1% w/w carrageenan, and 1% w/w chitosan.This combination has been found to produce a plant growth mediacomposition which significantly increases in strength over time, anddoes not contain cellulose fibers. Moreover, this combination includeseven less additive by weight than other combinations which producestrengthening compositions.

As shown in the examples herein, a plant growth media composition whichcomprises substrate materials and 2% w/w cellulose fibers, without otheradditives, results in only a slight increase in strength over time.

The additives, such as cellulose fibers, a combination of cellulosefibers and clay, alginate, chitosan, carrageenan, or combinationsthereof, can be used for making stabilized growing media for finalproducts such as substrate mixes, plugs, pre-compressed peat pellets,and the like. The term “substrate” may be used herein to refer to anysuch end product. The stabilized growing media can be prepared by firstcombining one or more substrate materials (e.g., a commerciallyavailable substrate mix) with cellulose fibers, or with cellulose fibersand clay, or with other additives or combinations thereof describedherein, to produce a fibrous mixture. The fibrous mixture can then beused to form pellets, plugs, pots, mini blocks, or the like by addingthe fibrous mixture to the desired mold (e.g., a tray having cavitiesfor producing blocks or pressing pots), though this shaping step is notnecessary if the desired product is a stabilized substrate mix insteadof a product having a defined shape such as a plug.

The substrate materials and additives are mixed together with a highshear speed. A high shear speed is important for optimal binding andhomogenous mixing. A standard handheld kitchen mixer is suitable forproviding a high shear speed, though other methods of mixing with a highshear speed are encompassed within the present disclosure. Moreover,high shear mixing is not strictly necessary, and compositions which havenot been mixed at a high shear speed are nonetheless encompassed withinthe present disclosure.

Once the fibrous mixture is adequately mixed together, the fibrousmixture is optionally compressed. For example, the fibrous mixture canbe made into compressed pellets. Compression enhances the binding of thefibrous mixture. The compressed fibrous mixture is useful fordo-it-yourself substrate plugs, where the end user simply fills a traywith the fibrous mixture and then adds water to produce a plug. It hasbeen found that the fibrous mixtures described herein get stronger overtime and repeated watering cycles, and therefore are highly desirablefor do-it-yourself plug applications, which provide flexibility forgreenhouse users.

The fibrous mixture generally has an initial (i.e., before additionalwater is added) moisture content ranging from about 20% to about 60%, orfrom about 30% to about 50%, or from about 35% to about 45%, based onthe total weight of the fibrous mixture. In one non-limiting example,the fibrous mixture has an initial moisture content of about 40%, basedon the total weight of the fibrous mixture.

Once the fibrous mixture is in the desired shape or form, water isgenerally added to the fibrous mixture to activate binding in thefibrous mixture and produce a stabilized growing media. The water may ormay not be heated. In some embodiments, water is added to the point ofsaturation, where water precipitates. Preferably, water is added untilthe point of ‘stickiness’, which is typically when the mixture has amoisture content ranging from about 55% to about 80%, or from about 60%to about 75%, or from about 65% to about 70%. However, different amountsof water can be added based on the desired physical characteristics ofthe final product. Moreover, the skilled practitioner will recognizethat the optimal moisture content of the fibrous mixture before andafter adding the water will depend on the compositions and amounts ofthe substrate materials and additives included in the fibrous mixture.Following the addition of water, the mixture is allowed to dry for ashort period of time, generally ranging from about 30 minutes to about 2hours. After drying, the resulting product is a stabilized growing mediain the desired form or shape. The use of additives such as cellulosefibers, a combination of cellulose fibers and clay, carrageenan, acombination of cellulose fibers and carrageenan, chitosan and/oralginate, or a combination of cellulose fibers and chitosan and/oralginate, as described results in a stabilized growth media havingadvantageous binding properties. For instance, as demonstrated in theexamples here, the stabilized growth media gains strength over time overrepeated watering cycles which mimic greenhouse conditions.

For clarity, the term “stabilized growing media” is used herein to referto the stabilized product, which is distinguishable from the fibrousmixture. The term “fibrous mixture” is used to refer to the productresulting from the combination of additives/binders with one or moresubstrate materials, before addition of water to activate binding. Forclarity, it is noted that the term “fibrous mixture” is used herein toencompass the mixture produced from substrate materials andadditives/binders even if the mixture does not include cellulose fibers.The term “stabilized growing media” is used herein to refer to theproduct resulting from the addition of water to the fibrous mixture toactivate binding therein. The term “plant growth media composition” isused herein to refer to either the fibrous mixture or the stabilizedgrowing media.

The conductivity (EC) and acidity (pH) are two commonly measuredcharacteristics of a substrate. The pH of the stabilized growing mediadescribed herein generally ranges from about 5.5 to about 7.0, or fromabout 6.0 to about 6.8, or from about 6.2 to about 6.6. The conductivityof the stabilized growing media described herein generally ranges fromabout 0.2 mS/cm to about 0.8 mS/cm. In one non-limiting example, thestabilized growing media has a pH of about 5.8, and a conductivity ofabout 0.5 mS/cm. Both the pH and the conductivity of the stabilizedgrowing media, or the fibrous mixture, are adjustable upon addition ofsuitable buffers or fertilizer ions.

In addition the various additives discussed above, the plant growthmedia composition provided herein may further include one moreadditional binders, such as the polymeric binders polyvinyl alcohol(PVA) or polyvinyl acetate (PVAC). The plant growth media compositionmay also include a variety of optional additives. These additionalbinders and additives can be added to the fibrous mixture or may bepresent in the substrate materials before combining with the additivessuch as cellulose fibers. When a polymer is present, a crosslinker canbe added to improve the strength of the media. The crosslinkers helpstabilize the plant growth media composition when a polymer is present.

Suitable crosslinkers for PVA include, but are not limited to,tripolyphosphate, citric acid, glyoxal, dimethylol dihydroxy ethyleneurea (DMDHEU), aldehydes, thermo setting resins, salts of multi-variantanions, glyoxal, isocyanate, poly(acrylic acid), bis(hyudroxyethyl)sulfone (BHES), glutaraldehyde, succinic acid, butane tetracarboxylicacid, alumina, epichlorohydrin, borax, aluminum hydroxide, hydratedaluminum chloride, aluminum acetate, aluminum sulfate, glycine, malicacid, tartaric acid, oxalic acid, dialdehydes, polyaldehydes, epoxides,triphosphates, divinyl sulphone, thiol reagents, and C2 to C9polycarboxylic acids. Non-limiting examples of commercially availablecrosslinkers include Bacote −20 (Magnesium Elekton, Ltd), Glyoxal(BASF), and Polycup 172 (Ashland). The crosslinkers can be used alone oras a part of a mixture of crosslinkers. In some embodiments, thecrosslinker is pre-mixed with PVA prior to being added to the substratematerials, to the fibrous mixture, or to the stabilized growing media.Pre-mixing the crosslinker and PVA speeds up the reaction.

Suitable crosslinkers for carrageenan, chitosan, or alginate include,but are not limited to, chitosan (which has hydroxyl groups capable ofcrosslinking to form, e.g., esters with carboxylic acid groups),calcium, glutaraldehyde, metals, adipic dihydrazide, water solublecarbodiimide, or combinations thereof. In some embodiments, thecrosslinker is pre-mixed with carrageenan, chitosan, and/or alginateprior to being added to the substrate materials, to the fibrous mixture,or to the stabilized growing media.

In one non-limiting example, the plant growth media compositioncomprises substrate materials, cellulose fibers in an amount rangingfrom about 0.5% w/w to about 2% w/w, carrageenan in an amount rangingfrom about 0.5% w/w to about 2% w/w, chitosan in an amount ranging fromabout 0.5% w/w to about 2% w/w, and tripolyphosphate in an amountranging from about 0.5% w/w to about 2% w/w.

Further, one or more accelerators can be added to the substratematerials, to the fibrous mixture, to the stabilized growing media inorder to benefit the crosslinking process. Suitable acceleratorsinclude, but are not limited to, sodium hypophosphite. The accelerator,when used, is typically added in an amount of about 1-10% relative tothe amount of crosslinker present. For example, if the crosslinker iscitric acid at 2%, then 0.2% sodium hypophosphite can be added as anaccelerator.

The terms “polyvinyl alcohol” and “PVA” refer to a water-solublesynthetic polymer having the general formula [CH₂CH(OH)]_(n). PVA may besupplied as a solid or as an aqueous solution. In particularembodiments, PVA is provided as a superfine grade solid having 99%purity. (When PVA is used as a solid, it can optionally be heated for aperiod of time in order to aid dissolution of the PVA in water.) PVA canbe manufactured from hydrolysis of polyvinyl acetate. PVA can be fullyhydrolyzed (all —OH groups), but may also be only partly hydrolyzed(e.g., 85-90% —OH groups) with, for example, 10-15% acetate groups.Suitable examples of commercially available PVA include, but are notlimited to: Selvol 165SF (Sekisui), which has a viscosity of 62-72 cps(high molecular weight); Selvol E575 (Sekisui), which has a molecularweight between 180,000-215,000; Selvol 350 (Sekisui), which has aviscosity of 62-72 cps and a molecular weight between 172,000-186,000;Selvol 707 (Sekisui); and Selvol 605 (Sekisui). Premade solutions of PVAmay be purchased from various companies. Such solutions with highmolecular weight or a high degree of polymerization are desired to giveadded strength. Examples from Sekisui are Selvol 125 (8% w/v solution),Selvol 325 (9% w/v solution), Selvol 523 (9% w/v solution), and Selvol540 (5% w/v solution). Alternatively, PVA can be added as a solidadditive.

PVA can be made as a solution (for example, 2-5%) before being added,since the solubility of PVA requires stirring and heating to 90° C. forsome time to make sure that the chemical is completely dissolved. Thesolution can then be added to the substrate materials, or to the fibrousmixture, or to the stabilized growing media. For convenience, PVAsolutions or PVA emulsions can also be purchased as premadesolutions/emulsions.

The terms “polyvinyl acetate” and “PVAC” refer to an aliphatic polymerhaving the general formula [C₄H₆O₂]_(n). PVAC generally has a whitecolor, is insoluble in water, and is sold as an emulsion. Suitableexamples of commercially available PVAC include, but are not limited to:VA710 emulsion, which is 50% solids per liter; Aquence LA 0276 emulsions(Henkel); DARATAK® 56L (Owensboro Specialty Polymers, Inc.), which is avery high molecular weight PVAC polymer with a low emulsion viscosityand good tensile strength; and Duracet 300 (Franklin Adhesives &Polymers), which is a PVAC with high molecular weight.

PVA can be made from PVAC by the use of NaOH/Methanol. PVAC has a whitecolor, while PVA is a transparent solution. PVAC is insoluble in waterand is sold as an emulsion, while PVA is 100% soluble in water. PVA maybe fully hydrolysed (all —OH group), but may also be partly hydrolysed(85-90% OH-groups and 10-15% acetate groups). Thus, PVAC is morehydrophobic and contributes stronger to produce drier surfaces than PVA.The strength of the polymer is dependent on the degree ofpolymerization; longer polymers or higher molecular weights givestronger products. A PVAC emulsion can be added to the substratematerials, or to the fibrous mixture, or to the stabilized growingmedia.

In one embodiment, the PVAC is Aquence LA 0276. However, other types ofPVAC emulsions may be used, such as: PVAC Emulsions like Duracet 300from Franklin Adhesives & Polymers, and Daratak 56 L from OwensboroSpecialty Polymers.

The additional binder can also include a foam. PVA foam or PVAC foam maybe made in the laboratory by mixing, for example, 1% (w/v) solution ofPVAC with shaving foam (soap) in a ratio of 1:1. PVA foam can also beprepared by whipping PVA vigourously. In one non-limiting example ofpreparing and using PVA foam from whipping, 100 ml 5% (w/v) Sekisui 540PVA and 8% (per weight PVA) crosslinker (citric acid) are whipped in amixing bowl with a typical kitchen hand mixer. Once the solution iscompletely foamed, the foam can be added to the substrate materials orto the fibrous mixture, and then mixed until a “creamy” texture isobtained. The resulting slurry can then be used to fill a conventionalplant propagation tray.

PVA foam may also be purchased from Makura BV in the Netherlands. PVAfoam or PVAC foam is commercially available as a bonding agent forgluing paper and wood. For example, Makura B.V. sells foam solutionsunder the trademark Makutech®. The Makutech® foam PVA glue, from MakuraBV, looks and feels like a shaving cream, is strong and sturdy, and haslimited penetration into the materials. This also results in lessmoisture in the final product. Makutech® PVA foam has the sameenvironmental and fire behavior as unmodified non-foamable PVA.Combining this type of PVA foam with suitable cross linkers, like citricacid, results in faster kinetics and reaction time. Non-limitingexamples of other specific commercially available PVA foams fromMakutech® include SA 300 (specified modified PVA glue), and silica foamssuch as SI 300, SI 500, or SI 600. When PVA foam is used, the resultinggrowing media product is more airy and lighter in weight.

Other possible additives include plasticizers including, but not limitedto: glycerol, phthalate esters, ethylene glycol, diethylene glycol,polyethylene glycols, propylene glycols, polypropylene glycols,1,3-butylene glycol, 1,3-propanediol, urea, trimethylaminehydrochloride, pentanediol, block copolymers of polyoxypropylene,hexitols, and oxyalkylene derivatives of hexitols. The plant growthmedia composition may also include additives such as pH buffers,expanded polystyrene, urea formaldehydes, and microelements (e.g., iron,manganese, zinc, copper, boron, molybdenum, chloride, and nickel).

It is understood that the present disclosure can be embodied as part ofa kit or kits. A non-limiting example of such a kit comprises asubstrate mix and cellulose fibers, clay, carrageenan, chitosan,alginate, or a combination thereof, in separate containers, where thecontainers may or may not be present in a combined configuration. Manyother kits are possible, such as kits further comprising an additionalbinder or other additive in additional containers. The kits may furtherinclude instructions for using the components of the kit to practice thesubject methods. The instructions for practicing the subject methods aregenerally recorded on a suitable recording medium. For example, theinstructions may be present in the kits as a package insert or in thelabeling of the container of the kit or components thereof. In otherembodiments, the instructions are present as an electronic storage datafile present on a suitable computer readable storage medium, such as aflash drive, CD-ROM, or diskette. In other embodiments, the actualinstructions are not present in the kit, but means for obtaining theinstructions from a remote source, such as via the internet, areprovided. An example of this embodiment is a kit that includes a webaddress where the instructions can be viewed and/or from which theinstructions can be downloaded. As with the instructions, this means forobtaining the instructions is recorded on a suitable substrate.

Furthermore, the present disclosure can be embodied as pre-filledcontainers, such as trays or pots, ready for seed planting. In someembodiments, trays having cavities containing plugs composed of thestabilized growing media as described herein are provided. In otherembodiments, pots (such as, but not limited to, biodegradable pots)filled with the stabilized growing media are provided. It is understoodthat any suitable container can be at least partially filled with thestabilized growing media and such a container is entiretly within thescope of the present disclosure.

EXAMPLES Example I Materials and Methods

Polyvinyl alcohol (PVA) was purchased from Sekisui (Kentucky, USA; tradename—Selvol; superfine grade—99% purity). ARBOCEL® 400, FI 400, FIF 400,FT 400, and LIGNOCEL CO 3-6 (all long fibers with less risk of molding)were provided by J. Rettenmaier & Söhne (Rosenberg, Germany). Likewise,Lignocel PF (water retention), and Lignocel Flakes (for orchards) wereprovided by J. Rettenmaier (Rosenberg, Germany).

The plant substrate mix carrying the trade name Jiffy Seedling Mix #17-1was from Jiffy Products America (Lorain, Ohio). It was composed of 70%fine white peat, 20% perlite medium grade, and 10% vermiculite finegrade, in addition to lime, fertilizer, and wetting agent. To the 17-1substrate mix was added 0.26 liters of the wetting agent Conductor(Aquatrols Inc., Paulsboro, N.J.) per m³ mix. The pH was specified to bepH 5.8±0.3 and the EC was specified to be 0.5±0.3 mS/cm. The pH wascontrol measured to be 5.86. pH measurements of substrate mixes of plugswere taken by a dilution method, for example by diluting a fixed amountof substrate in a certain volume of water and measuring the pH in thewater. Typically, a 1:1.5 volume suspension of the substrate indemineralized water for 18 hours was used.

The Jiffy Blend #10 coir mix was composed of 70% coir, 26% Spaghnumpeat, and 4% perlite. The Jiffy Blend #3 mix was composed of 90% finepeat and 10% medium perlite.

A mix of plant substrates with chemicals was made by adding, forexample, 10 g solid Arbocel® FT400 or 20 g solid Arbocel® FT400, to 100g of either Jiffy Blend #10 or Jiffy Blend #3 substrate mix, makingsubstrate mixes with 10% (w/w) or 20% (w/w) Arbocel, respectively. Thefibrous mixtures containing Arbocel and substrate materials had 65.9%moisture content (MC). For making samples for texture analysis, thefibrous mixtures were added to a square frame, compressed, and preparedfor irrigation. The squares were measured on load/tensile strength.After filling, the load squares were matured for 24-96 hours, typically48 hours, at room temperature (21° C.). Temperature was measured with aDigital Thermometer Testo 110 from Testo, Inc. (Sparta, N.J.).

For making plugs for transplanting and plant growth experiments, thecellulose fibers were mixed into the substrate materials as detailedabove, and the resulting fibrous mixtures were used to fill the squarecavities. A 338-count injected molded tray was used. Each cavitycontained 20 cc. Water heated to specified temperatures was then addedto the mix until complete saturation occurred. The material was set for48 hours, and the cavities were tested in plant growth.

pH and EC Measurement

The conductivity of the substrate gives an indication about thenutritional level. An EC meter (Seven Easy EC Meter from Mettler-Toledo,LLC, Columbus, Ohio) was used to measure the conductivity. The acidityof the substrate was determined potentiometrically using an electronicpH meter (Seven Go pH meter from Mettler-Toledo, LLC, Columbus, Ohio).Both EC and pH were determined using one and the same 1:1.5 volumesuspension of the substrate in de-mineralized water.

Breaking Point Measurement using a Texture Analyzer

Breaking strength is the greatest stress, especially in tension, that amaterial is capable of withstanding without rupture. Tensile strength isthe maximum stress that a material can withstand while being stretchedor pulled before failing or breaking. Breaking force in Newtons wasrecorded over time/distance at 20-22° C. A Lloyd Instruments LF-plussingle column universal testing machine from Lloyd Materials Testing(Bognor Regis, UK) was used to measure the load/breaking strength of thesubstrate blocks treated with the PVA/CA and other compounds.Micro-processed control for highly accurate load measurement and rapiddata acquisition was implemented, including a highly accurate load cellthat is for tension, compression, and cycling through zero forcemeasurements. Load was measured in Newtons against machine extension inmillimeters (mm).

Plant Growth

Efficacy was tested by germinating and growing tomato plants in thestabilized growing media. Two tomato seeds (of ‘Beef Stake’) were placedin individual cells filled with fibrous mixture, irrigated, and placedinto a germination compartment. For vegetative propagation likeGeraniums, a 2 node length individual cutting was placed in theappropriate fibrous mixture. A propagation tray was then placed in atray and a tight cover simulating a greenhouse environment was utilized.To reduce the evapotranspiration rate, manual misting applications ofwater were applied 4-5 times daily. Typically, root initiation at thebase occurs in 7-10 days. Germination was determined and noted by visualinspection, when plant radicals were seen emerging from underneathsubstrate. After germination, the cover of the compartment was removedand plants were treated with 12 hours of supplemental lighting (6400 Kwavelength) and typical irrigation and nutrient solutions at 20-22° C.After 14-21 days, both the vegetative and root portions of theindividual plants were evaluated for any stress-related factors thatwould affect normal growth.

Results and Discussion

Plant plugs were made in situ with Arbocel® FT 400 (FIGS. 1-2). Theplugs were made by adding 200 grams of substrate materials to 300 ml ofwater, and then adding the volume of 5% Arbocel. This produced coherentand rather strong elastic plant plugs.

Load Testing with Texture Analyzer Testing with Soid Arbocel Mixed intoSubstrate

Different blocks with solid Arbocel and substrate materials weremanufactured and tested in break point measurement. Technically this isforce/breakpoint measurements, but a tensile property can be observedwith strength factor over distance.

Making Press Pots

Cellulose fibers (Arbocel) were added to the Preforma Blend #3. Aparallel production with PVA/Citric acid was also made. Water was addedto these fibrous mixtures (initial moisture content about 40%) until thepoint of ‘stickiness’ texture, having a moisture content of about65-70%. The mixes were then manually pressed to square press pots with amanual press pot maker The press was pushed into the mix in a containerand punched out, releasing mini blocks. The blocks were light and gainedstrength as they sat over time. The blocks held together very nicelyafter a very short resting time. The blocks were sowed with lettuce,cress, tomato, or basil.

The weight of the Arbocel or PVA blocks was compared to that of clayblocks. An average of 6 blocks from each series shows that the clayblocks are 9.3% more in weight than the PVA. This is based on using 200g of Jiffy Blend #3 substrate material. Tomatoes were seeded in all 3sets for germination and growth tests.

Shrinkage Test

10 press pots were made and compacted into a row. The length of eachpress pot was measured when freshly made, and then again after a periodof time, for example 1-2 weeks, when the pots were dry. Thesemeasurements showed that there may only be 1 cm of shrinkage for 10blocks, measuring the total length of a ‘road length’ made of 10-25blocks.

Rooting

Arbocel® powdered cellulose FT 400 (10% per weight) was added to thesubstrate Jiffy Blend #3. The fibrous mixture was blended and thenfilled into a traditional horticultural propagation growing tray. Waterwas added to the fibrous mixture, in which the material then providedstructural stability. Planted cuttings were then placed into a mini labgreenhouse where traditional growing conditions were applied. FIG. 3shows a photograph of vegetative geranium cuttings showing extensionroot development in the substrate 8 days after initiation (or “sticking”un-rooting cuttings). Typically, this extension root developmentrequires a longer period, generally 10-14 days, depending on greenhouseconditions. Thus, the stabilized growing media resulted in surprisinglyfast rooting.

Summary

Arbocel is not water soluble and cannot be washed out of the plug. Thebinding to growing media does not depend on excessive heating, and thebinders can be added to different types of growing media such ashorticultural mixes filled in tray cavities/cells, systems for makingpress pots, expansions of quick soil mixes (QSMs)—precompressed peat orcoir squares and plates, and of netless pellets systems. Many of theseapplications are suitable for vegetable growing. These compositionsresult in such stabilized media that they may be planted directly in thefield.

Example II

Substrates were prepared by weighing 200 grams of Jiffy Blend #30, whichcontains 70% Canadian sphagnum peat, 20% coir, and 10% perlight, on asymmetry digital scale. (FIG. 4A.) Arbocel® H1000 cellulose fibers (J.Rettenmaier, Schoolcraft, Mich.) were added in an amount of 2% w/w tothe Jiffy Blend #30. (FIG. 4B.) The materials were mixed together usinga standard handheld kitchen mixer at a high shear mixing speed toseparate and mix the H1000 into the Jiffy Blend #30 substrate material,creating a fibrous mixture. (FIGS. 5A-5B.) The fibrous mixture was thencompletely filled into an empty horticultural plant propagation tray.The substrate was slightly compacted to eliminate any voids, and tophysically compress the fibers together. Water was then applied to thefibrous mixture until the cavity was completely saturated and excesswater started to precipitate out of the bottom drainage hole of thetray. (FIG. 6.)

Three additional trays were prepared as described above, with differentadditives or combinations of additives. Of the four total trays, onetray was filled with a fibrous mixture made from Jiffy Blend #30 andH1000 cellulose fibers, one tray was filled with a fibrous mixture madefrom Jiffy Blend #30 and a cellulose fiber material having recycledcolor magazine print and a minute amount of clay (referred to as “ETF”),one tray was filled with a fibrous mixture made from Jiffy Blend #30 andkappa-carrageenan (“Carrag”), and one tray was filled with a fibrousmixture made from Jiffy Blend #30 and both H1000 cellulose fibers andPelbon clay (“H/Clay”).

The trays were allowed to sit 24 hours before evaluating the modulusbreak force characteristics. Then, plugs were removed from the trays andtested in a IMADA modulus testing device. (FIG. 7A.) Pressure wasapplied until the break point was reached. (FIG. 7B.) Measurement of thebreak point were taken in two series, and were measured in LBF(pound-force) with 1 LBF equaling 4.5 N. The results are shown in FIG.7C and the following Table 1.

TABLE 1 Measurement of break point in LBF (1 LBF equals 4.5N) H1000 ETFCarrag H/Clay Series 1 3.8 2.9 1.7 4.2 Series 2 3.6 2.5 1.4 3.9

As seen in FIG. 7C and Table 1, the plugs made with the H1000 showedhigher force strength, which was also increased with the addition ofPelbon clay from AMCOL Bio-Ag (Hoffman Estates, Ill.) to the H1000. Inother words, the strongest of the plugs were those having a combinationof cellulose fibers and clay. Without wishing to be bound by theory, itis believed this is because the colloids in both the peat and clayincrease their amount of connections with the binding effect increasewith the reduction of ‘free water’. Pelbon has a high cation exchangecapacity (CEC), which also contributes to strong binding of the cations.The benefits of these plugs include nutrient management and compactplant growth.

Plants (geraniums) were grown in the plugs prepared as described above.FIG. 8 shows a photograph comparing the plugs at 2.5 weeks from stickingof un-rooted cutting. In FIG. 8, the H1000 plug is on the left, and theH1000/clay plug is on the right. As seen from this image, the H1000/clayplug held together better than the H1000 plug. Thus, the combination ofcellulose fibers and clay produces a substrate with better bindingproperties than cellulose fibers without clay. Furthermore, the plant onthe right in FIG. 8 has a better developed root structure than the planton the left. In other words, the plant grown in the H1000/clay plug wasmore developed than the plant grown in the H1000 substrate,demonstrating that plant development is enhanced from the combination ofcellulose fibers and clay more than cellulose fibers without clay.

An additional tray was made in the manner described above where one rowof voids was filled with a fibrous mixture made from Jiffy Blend #30 andETF, one row was filled with a fibrous mixture made from Jiffy Blend #30and an alternative cellulose fiber product referred to as 105B, one rowwas filled with a fibrous mixture made from Jiffy Blend #30 and anundisclosed binder material, and one row was filled with a fibrousmixture made from Jiffy Blend #30 and a mixture of alginate andchitosan. FIG. 9A shows photographs of the tray, and FIG. 9B shows aphotograph of the plugs made from Jiffy Blend #30 and ETF. Notably, ETFincludes a trace amount of clay. FIG. 9A shows the trays filled withplants, and FIG. 9B shows the plugs removed from the trays, with theroots of the plants visible. As seen from FIG. 9B, these plugs heldtogether sufficiently well after 2.5 weeks of plant growth.

FIG. 10 shows photographs comparing plant growth in plugs whichincluded, from left to right in FIG. 10, ETF, 105B, an undisclosedbinder material, and a mixture of alginate and chitosan. As seen fromFIG. 10, each of these plugs held together sufficiently well after 2.5weeks of plant growth.

FIG. 11 shows a photograph comparing plant root development andsubstrate binding between a plug that included 2% w/w H1000 cellosefibers (on the left in FIG. 11) and a plug with no cellulose fibers (onthe right in FIG. 11), where each plug included Jiffy Blend #30.Normally, it takes about 4 weeks for secondary root development.However, as seen in FIG. 11, secondary root development had begun after2.5 weeks in the substrate that included cellulose fibers.

Simulated Greenhouse Environment

A greenhouse environment was simulated with six different plugs: JiffyBlend #30 without cellulose fibers or other additives, Jiffy Blend #30with H1000 cellulose fibers, Jiffy Blend #30 with Pelbon clay, JiffyBlend #30 with H1000 cellulose fibers and Pelbon clay, Jiffy Blend #30with chitosan (1% w/w of substrate material) and alginate (1% w/w ofsubstrate material), and Jiffy Blend #30 with kappa-carrageenan. Thegreenhouse was simulated by drying with an oven, and watering the plugsevery 2 hours after an initial 24 hours. The breakpoint of the plugs wasmeasured after the initial 24 hours, then at 2 hours, 4 hours, 6 hours,and 8 hours of the greenhouse simulation. These results are displayed inTable 2 below.

TABLE 2 Breakpoint of plugs after watering and drying cycles in LBF (1LBF equals 4.5N) 24 hours 2 hours 4 hours 6 hours 8 hours Std 2.16 2.132.11 2.28 2.27 H1000 3.06 3.39 3.78 3.74 3.89 Pelbon 3.01 3.19 3.25 3.243.20 H/P 3.03 3.14 3.85 3.88 4.03 Chito/Alg 2.98 2.98 3.28 3.45 3.80Carrageen 3.02 3.2 4.16 4.88 4.40

As seen from Table 2, an increase in strength was observed over thecourse of the watering and drying cycles for each of the plugs, but thestrength was most significantly enhanced with the H/P plug and thecarrageenan plug. This demonstrates that the combination of cellulosefibers and clay provides an enhanced strength increase over time ascompared to cellulose fibers without clay or clay without cellulosefibers. The carrageen plug and the chitosan/alginate plug also exhibitedmarked enhancements in strength over time.

Example III

Plugs were made from the following combinations using theabove-described methods: (1) Jiffy Blend #30 and 2% w/w H1000; (2) JiffyBlend #30, 2% w/w H1000, and 2% w/w kappa-carrageenan; (3) Jiffy Blend#30, 1% w/w kappa-carrageenan, and 1% w/w chitosan; (4) Jiffy Blend #30,1% w/w H1000, 1% w/w kappa-carrageenan, and 1% w/w chitosan; (5) JiffyBlend #30, 1% w/w H1000, 0.5% w/w kappa-carrageenan, and 0.5% w/wchitosan; (6) Jiffy Blend #30, 0.5% w/w H1000, 0.5% w/wkappa-carrageenan, and 0.5% w/w chitosan; and (7) Jiffy Blend #30, 0.5%H1000, 0.5% kappa-carrageenan, 0.5% w/w chitosan, and 1% w/wtripolyphosphate (crosslinker). The plugs were allowed to sit for 24hours prior to break point testing, and then watered and tested every 2hours. The plugs were kept in a simulated greenhouse environment, at atemperature between 70-80° F. over the course of the drying time. Table3 below displays the breakpoints measured after the initial 24 hours,then at 2 hours, 4 hours, 6 hours, and 8 hours of the greenhousesimulation.

TABLE 3 Breakpoint of plugs after watering and drying cycles in LBF (1LBF equals 4.5N) 24 hr 2 hr 4 hr 6 hr 8 hr H 1000 2% 3.10 3.31 3.58 3.603.62 H1000 2% + Carrageenan 2% 3.81 3.90 4.65 7.11 7.08 Carrageenan 1% +Chitosan 1% 3.19 3.52 3.55 5.43 5.45 H1000 1% + Carra 1% + 3.82 4.025.01 6.43 5.97 Chito 1% H1000 1% + Carr 0.5% + 3.38 3.98 4.45 5.01 5.00Chito 0.5% H .05% + Carr 0.5% + 3.12 3.27 3.64 3.83 3.86 Chito0.5%w/tripoly

As seen in Table 3, plugs containing carrageenan exhibited a similartrend as plugs containing clay, namely, displaying enhanced strengthfollowing repeated watering and drying cycles. Plugs having combinationsof carrageenan and cellulose fibers, as well as the combination ofcarrageenan and chitosan, gained significant strength over time. Thecombination of cellulose fibers and carrageenan, in particular,demonstrated a significant gain in strength over the course of thetesting period, more than doubling from 3.81 LBF to 7.08 LBF. This showsthat such plugs would gain strength over the course of the traditionalcrop time of 4-6 weeks in the greenhouse environment. This is alsoimproved with the root entanglement in the plug over the course of thecrop time.

Certain embodiments of the compositions and methods disclosed herein aredefined in the above examples. It should be understood that theseexamples, while indicating particular embodiments of the invention, aregiven by way of illustration only. From the above discussion and theseexamples, one skilled in the art can ascertain the essentialcharacteristics of this disclosure, and without departing from thespirit and scope thereof, can make various changes and modifications toadapt the compositions and methods described herein to various usagesand conditions. Various changes may be made and equivalents may besubstituted for elements thereof without departing from the essentialscope of the disclosure. In addition, many modifications may be made toadapt a particular situation or material to the teachings of thedisclosure without departing from the essential scope thereof.

1. A plant growth media composition comprising: one or more plant growthsubstrate materials comprising coir, peat, and perlite; cellulosefibers; and clay.
 2. The plant growth media composition of claim 1,wherein the plant growth substrate materials further comprise one ormore of pine or other barks, compost, fertilizers, vermiculite, manure,granulated lava, pumice, burnt or calcined clay, mineral fibers,Hypnaceous moss, rice hulls, bagasse, sand, leaf mold, gypsum, andlimestone.
 3. The plant growth media composition of claim 1, wherein thecellulose fibers are present in an amount ranging from about 0.1% w/w toabout 40% w/w. 4-5. (canceled)
 6. The plant growth media composition ofclaim 1, wherein the cellulose fibers comprise a mixture of celluloseand lignocellulose. 7-11. (canceled)
 12. The plant growth mediacomposition of claim 1, wherein the cellulose fibers have an averagelength that ranges from about 10 μm to about 5 mm, and an average widththat ranges from about 1 μm to about 500 μm.
 13. The plant growth mediacomposition of claim 1, wherein the cellulose fibers have a densityranging from about 0.5 g/cm³ to about 5 g/cm³, an equilibrium moisturecontent ranging from about 5% to about 15%, and a length-to-width ratiogreater than about
 10. 14-15. (canceled)
 16. The plant growth mediacomposition of claim 1, wherein the plant growth media composition has amoisture content, before addition of water, of from about 35% to about45%.
 17. The plant growth media composition of claim 1, furthercomprising a sufficient amount of water to render the moisture contentof the plant growth composition in a range of from about 65% to about70%.
 18. The plant growth media composition of claim 1, furthercomprising a wetting agent.
 19. The plant growth media composition ofclaim 1, wherein the plant growth media composition has a pH rangingfrom about 5.5 to about 6.8.
 20. (canceled)
 21. The plant growth mediacomposition of claim 1, further comprising an additional binder selectedfrom the group consisting of polyvinyl alcohol (PVA) and polyvinylacetate (PVAC).
 22. The plant growth media composition of claim 21,further comprising a crosslinker. 23-24. (canceled)
 25. The plant growthmedia composition of claim 1, wherein the plant growth media compositionis in the form of compressed or expanded pellets, flat filled trays,mini blocks, or press pots.
 26. (canceled)
 27. The plant growth mediacomposition of claim 1, wherein the clay comprises bentonite clay. 28.The plant growth media composition of claim 1, wherein the cellulosefibers and clay are present at a weight ratio of cellulose fibers toclay ranging from about 1:1 to about 5:1.
 29. The plant growth mediacomposition of claim 1, wherein the clay is present in an amount rangingfrom about 10 kg/m³ of substrate materials to about 65 kg/m³ ofsubstrate materials.
 30. (canceled)
 31. A method of making a stabilizedgrowing media, the method comprising: mixing cellulose fibers and claywith one or more plant growth substrate materials to form a fibrousmixture, wherein the one or more plant growth substrate materialscomprise coir, peat, and perlite; configuring the fibrous mixture into adesired shape; and adding water to the fibrous mixture to activatebinding of the fibrous mixture and produce a stabilized growing media ofthe desired shape.
 32. The method of claim 31, further comprisingallowing the stabilized growing media to dry for a period of timeranging from about 30 minutes to about 24 hours. 33-36. (canceled) 37.The method of claim 31, wherein the mixing comprises homogenously mixingwith a high shear speed.
 38. The method of claim 31, further comprisingcompressing the fibrous mixture prior to configuring the fibrous mixtureinto the desired shape. 39-40. (canceled)